With the rapid development of digital cameras and scanners, digital photographs are becoming a commodity, especially since the cost of taking a digital photograph is virtually free of charge. As a result, digital photographs can accumulate rapidly and automated tools for organizing digital photographs have become extremely desirable. Unfortunately, and even in view of the extensive research in face detection and recognition in computer vision that has been performed to date, there are still no commercial products available for effectively organizing digital photographs of individuals in everyday situations (e.g., photos in a family photo album) by annotating semantics of photographic content.
In part, this is because of the great difficulty of generating an acceptable algorithm for contending with the complexity of human perception for face recognition. It is still not clear how people recognize faces and how they remember previously viewed faces. Such complexities of facial recognition are further exacerbated when photographs are subject to non-homogenous lighting conditions, do not include frontally aligned faces, and/or contain large variation in facial expression across multiple photos. However, most family album photo scenarios are taken under such non-ideal, or non-studio controlled conditions. It very difficult to establish a reliable face model of an individual unless it is frontally aligned, subject to substantially homogenous lighting conditions, and contains small variation in facial expression from one photo of the individual to another. Moreover, generally it is not practical to ask a user to collect a large number of well aligned sample faces to train an accurate model of an individual. Each of these factors contributes to the inaccuracy of conventional facial recognition algorithms.
For these reasons, no effective face recognition solution for automated annotation of family photographs that include faces is available at this time. As a result, semantic annotation of faces in digital photos is still left to the user. As can be appreciated, such a task can be substantially tedious (i.e., labor intensive and time consuming), especially considering that large accumulations of digital photographs, such as those in a family album, are commonplace.